Still, I think it's unrealistic to expect GitHub to parse through all of their logs. First, it would be non-trivial to detect the malicious behaviour in the first place, and secondly, keeping logs that go back multiple years is certainly non-standard, particularly at the info level.
Shocking because it will produce extremely large amounts of data, makes the logs extremely security-relevant, and probably breaks all kinds of privacy laws. E.g. in the EU a user has a right to request that a company delete all data they have collected about him. So you'd have to go through your logs and purge all request data from that user - possible, but likely to be overlooked.
